I now have a wing tube with an acceptable fit. Thanks to some suggestions here and some perseverance.

The ally tube has been smoothed with 600 wet n dry used wet, especially at the ends to be absolutely sure there's no burr.

But the most difference has been made by making my sanding tube a tighter fit. This is 120 grit aluminium oxide paper wrapped until it's a tight fit inside the wing. Obviously this applies more "sanding pressure" than previous attempts.

Danny. One quick look at that screen shot above and I see a programming mistake. Somehow we've ended up with some flap compensation with the wrong source. The + line just below CH3 is adding to the elevator, but it's sourced from rudder! Thankfully the amount is zero % so it will have no effect.

If you use HDMI then it probably has to be connected, as Adrian alluded to, to an HDMI socket that has ARC. It's likely that only one of the HDMIs on the TV has this so you may have to try them all and/or you may have to enable ARC.

(ARC means Audio Return Channel. Intended for sending audio from a TV "back" to say a Blue Ray player / surround sound system which would usually be "sending" signals to a TV).

If you're really lucky this link might even turn your soundbar on and off automatically too.